A Class 1 recall is the highest risk category and is issued when there is a "reasonable probability that eating the food will cause health problems or death," according to the USDA's web site.

The USDA's Food and Safety Inspection (FSIS) service "strongly encourages consumers to check their freezers and immediately discard any product subject to this recall," the recall announcement reads.

The following products, all of which have a "Best Before or Freeze By" date of Sept. 12, 2011, and "245D" ink jetted along the package seam, are included in the recall:

5 pound chubs of Kroger-brand "GROUND BEEF 73% LEAN - 27% FAT." These were produced on Aug. 23, 2011, and were packed in cases marked "D-0211 QW." The cases shipped to distribution centers in Indiana and Tennessee for retail sale.

3 pound chubs of Butcher's Brand "GROUND BEEF 73% LEAN - 27% FAT." These were produced on Aug. 23, 2011, and were packed in cases marked "D-0211 LWIF." The cases shipped to distribution centers in North Carolina and South Carolina for retail sale.

The E. coli contamination was first reported to the FSIS on Sept. 26 by the Ohio Department of Health. Ohio officials had collected contaminated ground beef from the Butler County homes of people who had taken ill after eating it. The investigation is ongoing.

Infection from the E. coli 0157:H7 bacterium can cause bloody diarrhea, abdominal pain, cramping or tenderness, dehydration, and in some people, fever, nausea, and vomiting. These symptoms usually start about three to five days after infection. Extreme cases can lead to fatal kidney failure. Those most susceptible to E. coli infection include the very young, the elderly, and those with weak immune systems.

E. colifood poisoning can be prevented by safely handling raw meat and by cooking ground beef to an internal temperature of at least 160 degrees Fahrenheit, which kills the bacterium.

The USDA is directing consumers with questions to contact Tyson at (866) 328-3156. A complete list of retail outlets involved in the recall can be found here: www.fsis.usda.gov/PDF/RC_077-2011_Retail_List.pdf.